1. Field of the Invention
The present invention relates to a PC card which is inserted into a card slot of a personal computer, for example, in order to extend the functions of the personal computer.
2. Description of the Related Art
In general, a personal computer is made up mainly of a computer body having an operation function, a memory function, and the like, a key board for inputting a signal to the computer body, a memory including a floppy disk and the like for storing memory in the computer body, and a display for indicating a program, an operational result, and the like.
Furthermore, the personal computer is provided with a card slot into which a PC card can be additionally attached in order to extend the memory contained in the computer body, add a modem, and the like. The size and shape of the PC card is specified by PC Card Standard and Standard by JEIDA(Japan Electric Industry Development Association).
As the binary unit of information content to be processed by the personal computer, a 32-bit byte has been gradually employed instead of a 16-bit byte in order to enhance the processing speed. Accordingly, there are two types of PC cards with respect to their size and shape, that is, 16-bit PC cards and 32-bit PC cards. Similarly, card slots on the personal computer side are roughly divided into two groups, that is, 16-bit and 32-bit card slots.
Furthermore, in order to reduce the consumption electric power, the driving voltage for the computer body has been changed from 5.0 V to 3.3 V. For ordinary uses, the driving voltage for 16-bit PC cards is set at 5.0 V, while that for 32-bit PC cards at 3.3 V. The driving voltage has been reduced from 5. 0 V to 3.3 V, so that it is necessary to secure the transmission or reception of a signal between the PC card and the personal computer. Therefore, the 32-bit PC card and the card slot are provided with ground electrodes having plural protuberances for tight grounding.
The respective PC cards are provided with a card key groove formed on the left-hand side thereof, viewed in the insertion direction, so that the PC cards can be prevented from being wrong inserted, turned inside out, and can be distinguished between 16-bit and 32-bit PC cards. The card-side key groove of the 16-bit PC card is so formed as to be wider than that of the 32-bit PC card.
With this card key groove, the 16-bit PC card can not only be inserted into the 16-bit card slot but also into the 32-bit card slot. On the other hand, the 32-bit PC card, though it can be inserted into the 32-bit card slot, is prevented from being inserted into the 16-bit card slot. That is, the respective protuberances of the ground electrode provided for the card slots of the 32-bit PC card prevent the 32-bit PC card from being inserted into the 16-bit card slot which has no parts for receiving the protuberance, and protects the ground electrode, the card insertion hole of the card slot, and the like.
The above-described conventional PC cards are provided with card-side key grooves formed in different sizes so that they can be distinguished between the 16-bit and 32-bit PC cards, and the 32-bit PC card can be prevented from being inserted into the 16-bit card slot, as described above.
On the other hand, PC cards which are available as both 16-bit and 32-bit cards are required. For the purpose of meeting this requirement, it is necessary to provide a PC card which can be inserted into both the 16-bit and 32-bit card slots, irrespective of the shapes and sizes of the card slots of personal computers.